The invention pertains to a card-holding device for the locking of a printed circuit card in a guide rail/rack of a subassembly/subrack or such, with a retaining element, that in case of a printed circuit card having been inserted into the guide rail lies in front of the front edge of the card and for withdrawing the printed circuit card can be swiveled out of the way against an elastic restoring force.
Printed circuit cards with electric or electronic components, which are mounted in subracks or other housings of the insertion technology, are normally guided on their longitudinal edges in guide rails, which makes it possible that they may simply be pushed into the subrack or the housing and pulled out again as needed.
Normally, the printed circuit card-holding devices are provided at their rear edge with plug and socket transfer connectors which establish the electrical connection with the subrack or the housing. Although the pinching effect of the plug and socket transfer connector, especially for multipole designs, holds the printed circuit cards in their inserted position, additional safety measures are required to hold the printed circuit card in its inserted position particularly for printed circuit cards not provided with a frontal plate piece and which, depending on the application, may be subjected to vibrations or irregular transverse accelerations. Separate card-holding devices serve this purpose.
A card-holding device of the type mentioned in the beginning is, e.g., known from the publication Hoffman/Schroff: "Katalog fur die Elektronik 96/97" (Catalog for electronics), pages 37.46 and 37.47: The card-holding device depicted there includes as retaining element an elastically deformable safety latch (shackle) that as a matter of choice has to be swiveled out of the way either by hand (e.g., with the thumb) or with an in/out lifting handle to allow pulling the printed circuit card out. The safety latch is here part of a component mounted in front of the guide rail in the area of a front module rack of a subassembly/subrack.
The disadvantage of the known card-holding devices is noticeable on insertion (push-in) of a printed circuit card into its guide rails: Since the safety latch of such a card-holding device, due to the elastic restoring force acting on it, reverts (moves) back to its idle position, i.e. the latched (locked) position as soon as the printed circuit card is completely pulled out, it interferes appreciably with the insertion of the printed circuit card: The printed circuit card must then not only be introduced into its two guide rails, but additionally the safety latch of the card-holding device has to be swiveled out of the way against the elastic restoring force in order to allow the insertion of the printed circuit card at all. This process gets to be especially cumbersome if card-holding devices are mounted on both guide rails for the acceptance of the printed circuit card.
Starting with this state of the art, the invention is based on the objective to improve a card-holding device of the type mentioned at the beginning such that it is only activated if a printed circuit card has been inserted into the associated subassembly/subrack or housing; i.e. the card-holding device should not hinder the push-in (insertion), especially the feeding of a printed circuit card into the associated guide rails.